1. Field of the Invention
The present invention relates, generally, to a vacuum generator systems and, more specifically, to a method for operating a vacuum generator system and a vacuum generator for carrying out the method.
2. Description of Related Art
Vacuum generators of various types are known in the art and are used for operating vacuum manipulator devices, e.g. so-called “ejectors”, which are operated with compressed air and draw in air with a suction connection. The generation of a vacuum occurs, for example, with a Venturi nozzle. Furthermore, electrically powered vacuum generators, e.g. vacuum pumps, are known in the art and generate a vacuum at a suction connection corresponding to an input variable (e.g. operational voltage and/or current).
As a result of the suction at the suction connection, a vacuum is provided to the vacuum manipulator device. Vacuum generators having an integrated monitoring device for the vacuum that has been generated are known from Published Patent Application Nos. DE 102007061820A1, DE102007058114A1, and EP 2080913A1. This enables a detection of the pressure at the suction connection, and makes it possible to indicate whether a pressure exceeds or falls below a threshold value via an electric signal. These signals can be used for implementing an Air Saving Control or an Energy Saving Control. For this, a valve in an ejector, for example, can be closed after a threshold value has been reached, and first re-opened when the pressure at the suction connection again exceeds the threshold value (in the following, a vacuum that has been attained at the suction connection will be referred to as a pressure that is lower than the ambient pressure).
A monitoring and energy optimization of this type is, however, prone to error. If, for example, the efficiency of the ejector changes, or the seal for the ejector develops a leak, or a leak occurs in the vacuum manipulator device connected thereto, then the given threshold value, in this case, would not be attained, or would be attained at a later point in time. The energy efficiency of the system would be impaired. Moreover, malfunctions could occur, e.g. if a workpiece could no longer be retained due to an insufficient vacuum at the suction connection. A method for the electrical processing of vacuum pressure data for a vacuum unit is described in Published U.S. Pat. No. 5,617,338. For this, pressure data is recorded by numerous sensors and compared with stored threshold values. However, there remains a need in the art for increasing the energy efficiency in vacuum manipulator systems of the specified type, and improving the reliability of the operation thereof.